Vehicle brake



Aug. 20, 1935. c. A. sAwTELLE VEHICLE BRAKE Filed Sept. 4, 1931 5 Sheets-Sheet l INVENToR CdrZeS Adwe//e BY y ATTORNEY a 20, 1935, K* c; A; sAwTELLE 2,012,025 VEHICL BRAKE Filed Sept. 4, 1931 f 3 Sheets-SheerI 2 INVENTR Cdr/es Acwelle BY ATTORNEY ug. zo, 1935.

C. A. SAWTELLE VEHICLE BRAKE Filed sept. 4, 1931 3 sheets-sheet 5 y .Q @L

INVENTOR E IZes Aczwe/e BY Patented Aug. 20,

, VEHICLE BRAKE Charles A. Sawtelle, Detroit, Mich., assigner, by

direct ,and mesne assignmentato S. andi?. Engineering Company, Detroit, Mich., a corpof yration'of Michigan g Application September 4, 1931, Serial No.' 561",l66

'1o claims. (omas-'78j v 1 Thisl invention relates to brakes and particularly motor vehicle brakes. Y. Y'

Anpbject of the invention is' to adapt a pluralityvof brake bands't'o engage the same drum,

5: and'tov establishan actuating'connection to said l5" ferential expansion, and permitting them, whenv applied, to 'fully conform to a' brake drum,despiteY the latter'by frictionally generated each' thereof bandssuch'as r'to equalize 'the forces applied to j" Another object isrto arrangesuch bands in a laterallyfadjoined relation, adapting -them tok engage ladjacent'annular regions of the sames'urfaceofa brake drum.'

to so connect said bands V- aSff-tonflantain them in'a definite lateral proxr imityto veach other while affording vthema dif- .Y wherein: 40

distortionv of li'eatlj i v :Still another object is to apply equalized forces 20' to the circumferentially spacedends-of a'group of laterally adjoined brake bands, substantially coeiitensivev circumferentially,

bands; if Y Y andi to further equalize Vthe forces individually appliedto said A still furtherl object is to adapt a retracting spring to act equally on each of a plurality of laterally adjacent brake bands, to effecttheir normal withdrawal from the same drum.'

and

thereby secure' correspondencaunder braking conditions,`inthe heat-induced distortion of the band-andy that of a drum against which the band isv stressed.

These and various other objects the invention attains by the construction hereinafter described, and illustratedin the'Jaccompanyingr drawings,

' Fig". 1 is a view in diametrical section of a brake drurnand twin band brake mechanism interiorly coacting with said drum, the sectionvbeing taken on thefline I-I of Fig. 2.

. Fig. 2 is a sectional elevation ofthe sama'taken Fig. 3 is a transverse sectional view ofthe drum and brake mechanism,taken on the line 3-3 of Fig. 4r is a. perspectiveview of bythe twin brake bands.v

the u nitV formed YFig. 5 is a View of laterally adjacent and relatively free ends of the twin bands', showing, to an exaggerated degree, how a hinge pin carried by said ends is angularly ,shifted to` afford ends relative Vcircumferential.travel. Y

said

Fig. 6 isa fragmentary, radial, sectional'view of va modified 'construction' of drum andi-band; showing the' latter' retracted. 1I y Fig. 7 is a similar View of'the same with the band applied to thedrum,showingV (with exagg'eration) a corresponding distortion of drum" and band, duetofrictionallheat. Y. i

- Fig. Sis a fragmentary radial section of a druml and band of further modified form, the band yloe-1 ing shown retracted. 10:5' Fig. 9 is a similar viewfof the same withthe band applied, the distortionl of drum and bandl due to frictionalheat being again exaggerated.

gFig'. 10 isa radial section of Y'a furthermodi-l A cationof drum and band,`showing theflatter reii 1g;J

` tract'ed. i

' Fig. 11 is a similarview, showing the band ap-'f plied,again exaggerating the corresponding distortion ofthe parts under frictional heat.

` Referring now moreindetail to the drawings, 2b*

of 'laterally' adjacent andcircumferentially co`r4` 25 extensive brake bands Bfand lcifeachprovided with the usual lining Il. Said bands closelyf'ad'- join each other, Awhile preferably not contiguous, this relation being maintainedprinarily by ythree metal links', 6, and l, connecting said bands at 30" lpoints approxii'natelyv one hundred 'land twenty degreesfapart. Said links areloosely riveted" (or otherwise attached) to'th'ebands, asv indicated at 8, allowing a circumferential sw'ingingof the links, permissive of a slight differential expansion' 353 of the tWo bands. Furthermore, thelooseness of saidV rivets affords such tilting of the links,V or differential radial travel of their extremities, as is incidental to a 'slight differential expansion of the two bands. i

At ccrrespondingends, the two bands-arecoii nected by a plate 9, .secured to the bands by.. rivets I0 or the like, and said plate is formedwith a pair'of spaced'barrels I I to receive a hinge pin I2. f r The other two ends vof the bands independently mount a pair of actuating members I3, apertured to jointly receive a hinge pin I4. f.

The pins I2 and YIll are loosely engaged by rela-- tively short arms I5 of a pair'of bell crank levers', 5

pivoted, at the junctures of their long andshort 55e;

arms, upon pins I 9, suitably rigidly carried by the usual non-rotative backing plate 20 of the drum.

The arm I1 is terminally engageable by a means (not-shown) for applying' a braking force, and is of a length to afford to said means a considerable leverage.

It will be noted'that the openings of the actuating members I31whi`ch receive the pin I4 are flared i slightly from their mid portions to their ends to allow such tilting of said pin, as is illustrated in Fig. 5, the bell crank arm lengaging said pin' the latter substantially midway between the; rivets 8 so as to equalize the'spring eiort applied4 to the bands. u u, n It. is aan irriportant` .advantage ofthe described construction that theba-nda is'capable of expanding to a slightly greater extent than the.

effort. A

' Also; under the described conditions, the*v pin I4 willf-act as an equalizi-ng leverin transmitting the;-

bandl. Thus'when under heatfof frictionythe rimer fla-ngeof thefdrulnv I is` distortedt. as' ex-A aggeratedly indicated indash lines in-k Fig.. Sarthe band 3a will conform itself, under braking stress, tofthe moreV highly 'expanded' portion of the drum, thus assuring eicient use. of theaentirebraking jomed band.- extremities, said; pin tilting circumferentia-llyas Fig'. 54 illustra-tes, tofeffect'equalization of the applied stresses, while expanding the,V

bands differentially. l

While: theillustrated friction tion` com'prehends thev usev of a;- larger numberlof bands, connected in a unitary; relation fon `dii-ler-z entiali expansion; Itis further to'be understood that a 'muitlple' band: mechanismY `suchaa's here disclosedi will confor-ni itselftofsuch drums( as are well: las: to that` It. is.I to be noted that actuation of.V the lever` |21 (ini the direction ofthe arrow 'irrFigf. 2*)l electsan eqpa-lized distributionffof' effort-*to the-two bell. V cranks and` thencetcrthe,- circumferentiallyspaced endsof. thefbandsgsince the arms. I Ii-v and*v H1 arein terengaged: at a point substantially midway betweenithe bell crank pivots.;

In 'thef modiedconstructiom shown in Figs. 6

andi af brake bandi 2=3` interiorlynengageable;

Y greater extent at said edgethan at its juncture with therdrum. head M'a.. under heat, said flange: areszslightly'toward its free edge, as exaggmstedlyf shown in Fig. 7. Consequently,`

anordinary brake band is associatedwitha drum of the type shown in Figs. 6 and 7, a lack oproperparallelisnn betweenthe drum and band amiconsequent sacrifice of. efficiency resultsfrom any considerable generationY of frictional heat. The: present. invention gradually reduces the thicknessI of the band from its edge adjacent tof thefdnwn headto itsedge adjacent the free edge.Y

on the drum, with, thevresult that frictional heat'- expandsthe brake band differentially in its differentannularfregions, according to the band. thickness in- `said regions and` constant parallel'- means .comprises two bands, it.` is'. tobe` understood that the inven-` Vperature conditionsis secured..

ism of drum and band is achieved regardless of working temperature conditions.

Figs. 8 and 9 illustrate a modification in which a drum comprising a head 25 and a rim 25a is reinforced at the free edge of, said rim by a radial, outwardly projecting annular flange 26. Under frictionalheat conditions, such a drum expands approximately as indicated Fig.. 8', the rim assuming a slight bow from the drum head to the ange 26. v

To compel the brake band 21 to distort correspondingly to said drum under frictional heat,

saidband is'given a minimum thickness in a circumferential plane midway between the band edges, and isprogressively increased in thickness toward said edges.v Said band responds expan- V sively toV heat dinerentially'in different circumferential area-s; according to the varying thickness, and yconsequently maintains parallelism with the drum rim regardless of varying working temperatures. 4 K

In the further modiiication shown inFigs510 and 1l., therey is employed-a drum A28 having the nature of an annulus-fl-anged annularl-y' outward as indicated at 29, in a. plane-'midway between the lateraledgesof vthe drum Anydesiredsuitable support (not shown) for the drum-engaged With:- the vange V29.5,Y Under frictional hea-t said drum is varcuatelydistorted asexaggelatedly shown iny10the .free edge portions expand: ing in yexcessof Vthe reinfo-rcedLcentrakportiony7 A` brake band. 30 interiorlyapplicable said dr-um-.is-compelled. torespond. to frictional heatl similarly to; said drum by,progressivelyreducing. the Vthickness-'of said band from-its central-Gira cumferential plane toeach lateral edge. V,Eyrelecting a proper angle between Vthe',diyergentainfner and outer faces of said band, a conformity. Y

ofthe vbandl 'to/fthe'` Vdrum under all. working. tem- It isa characteristic of allV the.. described con- 'struetionsfthat `a band or bands is (or are)4 adapt-,- ed: to fully-'conforme to a brake drum,whether or not the latter is distorted by frictional heat. It

has1-been-v found lthat the inventioneliminates a 'markedloss of eiliciency kwhich-has,heretofore characterized. bar-rel?. typefl brakes vwhen `appliedi under sufcie'nt :stress and for an adequatei timef interval to frictionally develop considerable-heat. While itis apparent that ,the illustrated-embed iment off-my" inv-ention` herein disclosedfis well calculatedto-adequately fulfill-the objects andA ad` vantagesv primarily stated, itisrv to be` noted `that the invention issusceptible to variation, modifi-I cationand change within the spirit and, scope of. the'subjoined claims'.

Whatl.v claim is: i., u l 1. The combination with aplurality of` expansible, arcuate brake bands, arranged inA lateral proximity toone another, of means connecting said` bandswatA a plurality of` circumferentially spaced peints. maintaining` their lateral;- proximity and -alordingfthem differential expansion.` Kv

2. The combination with a; plurality of expansible arcuate brake bands arrangedrrinmutual ,lateral proximity, .ofa plfurality of swinging links connecting saidrbands, andA spacedl circumferentially of the bands, vsaid links maintaining mutua-L lateral proximity` of-thebands while aording them differential expansion.. n l; f A f 3; The c'zombination'V with` a 'plurality ofsubstantiallycoextensive,'expansible, arcuate brake.- bandaarranged in mutual lateral proxiinitmofa. rigid connectionY betweenv corresponding` ends of..v said` bands, jointly ,carried/by the other ends of said bands for receiving an actuating force, said means affording-the bands a differential response toV such force. Y

4. The combination with a plurality of substantally coextensive, expansible, arcuate brake bands, arranged in mutuallateral proximity, of means connecting said bands, maintainingv their lateral proximity and affording themdiilerential expansion, and means terminally carried by said bands for applyingthe same actuating` force to both bands.

5. The combinations With a plurality vof substantially coextensive, expansible, arcuate brake.

bands, arranged in mutual lateral proximity, of

Va pair of lugs carried by correspondingfendsof said bands, having normally aligned openings and a pin mounted in said openings for transmitting an actuating force to both bands, said pin having a limited angular movement in said Y means for said bands having an engagement with the other ends of said bands, affording them differential expansion, and adapted4 toequalize the forces applied to the respective bands. l i

7. In a brake, the combination with twolaterally adjacent arcuate brake bands having corresponding laterally spaced ends, thrust-receiving elements mounted on said ends, an actuating member projecting between said elements, and a pressure equalizer connecting said thrust receiving elements and passing operatively through `said actuating member.

8. A brake, comprising a brake drum,` a plurality of laterally adjacent, substantially coeX- tensive, expansilole brake bands interiorly Yengageable with said drum, a spring retractively acting on all of said bands-and a member con- Y necting'said spring to the bands affording the bands a differential expansion.

9.'A brake comprising a brake drum, a plurality of laterally adjacent brake bands engageable with said drum, a spring retractively acting on all of said bands,-and means equalizing the l 'spring action on the several bands.

10. In a brake, the combination With two laterarcuate friction faces, of an operating member for both of said elements, and a. pin forming an ments having openings receiving said pin, said openings being ared from their mid portions to their ends, to allow tilting of said pin to equaliZe the forces transmitted to said elements.

` CHARLES A. SAWTELLE.

ally adjacent friction applying elements having -operating connection between said member and elements, the operating member and said ele- 

